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Alpha Cygni,Y Canum Venaticorum,Pistol Star,Doradus Stars and the Alpha Scorpii Binary Stars
Deneb (α Cyg, α Cygni, Alpha Cygni) is the brightest star in theconstellation Cygnus and one of the vertices of the Summer Triangle. It is the 19th brightest star in the night sky, with an apparent magnitude of 1.25. A blue-white supergiant, Deneb is also one of the most luminous nearby stars. Other names include Arided and Aridif, but these have fallen out of use. La Superba (Y CVn, Y Canum Venaticorum) is a star in the constellationCanes Venatici, well-known for its strikingly red appearance.La Superba is a semi-regular variable star, peaking at about +4.8 mag and diminishing to around +6.3 over a 160 day cycle. Known in short form as Y CVn, it is one of the reddest stars in the sky, and it is among the brightest of the giant red "carbon stars". It is the brightest J-star in the sky, a very rare category of carbon stars that contain large amounts of carbon-13(carbon atoms with 7 neutrons instead of the usual 6). 19th centuryastronomer Angelo Secchi, impressed with its beauty, gave the star its common name.[1]La Superba's temperature is believed to be about 2800 K, making it one of the coolest true stars known. Y CVn is almost never visible to the naked eye since most of its output is outside the visible spectrum. Yet, wheninfrared radiation is considered, Y CVn has a luminosity 4400 times that of the Sun, and its radius is approximately 2 AU. If it were placed at the position of our sun, the star's surface would extend beyond the orbit of Mars. The Pistol Star[1] is a blue hypergiant and is one of the most luminousknown stars in the Milky Way Galaxy. It is one of many massive young stars in the Quintuplet cluster in the Galactic Center region. The star owes its name to the shape of the Pistol Nebula, which it illuminates. It is located approximately 25,000 light years from Earth in the direction ofSagittarius. It would be visible to the naked eye as a fourth magnitude star, if it were not for the interstellar dust that completely hides it from view in visible light. R Doradus (also called HD 29712) is the name of a red giant Mira variable star in the far-southern constellation Dorado, although visually it appears more closely associated with the constellation Reticulum. Its distance from Earth is 178 ±10 light-years (55 ±3.1parsecs).[1] Having a uniform disk diameter of 0.057 ± 0.005 arcsec,[6] and given its distance, it is currently believed to be the star with the second largest apparent size as viewed from Earth (right after the Sun). The estimated diameter of R Doradus is 515 ± 70 million km (3.46 AU) or 370 ± 50[5] times the diameter of the Sun. If placed at the centre of the Solar System, the orbit of Mars and most of the main asteroid belt would be contained within the star. The visible magnitude of R Doradus varies between 4.8 and 6.6, which makes it usually just visible to the naked eye, but in theinfrared it is one of the brightest stars in the sky and its total luminosity is 6500 ± 1400 times that of the Sun.[7] S Doradus is one of the brightest stars in the Large Magellanic Cloud,[6] a satellite of the Milky Way. A hypergiant, it is one of the most luminous stars known (sometimes more luminous than −10 absolute magnitude), but so far away that it is invisible to the naked eye. This star belongs to its own eponymous S Doradus class of variable stars (these classes are usually named after their prototypes); also designated as the class luminous blue variable or LBV, of which S Doradus forms the archetype. S Doradus exhibits long, slow changes in brightness, punctuated by occasional outbursts. Although it has a nominal stellar classification of A0e, in 2000 it was found to have the spectrum of an F-type star (F0).[6] Antares (α Scorpii, α Sco, Alpha Scorpii) is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky. (It is sometimes listed as 15th brightest, if the two brighter components of the Capella quadruple star system are counted as one star.) Along with Aldebaran, Spica, and Regulus it is one of the four brightest stars near the ecliptic. Antares is a slow variable star with an average magnitude of +1.09.[3]